Answer:
13 cups
Step-by-step explanation:
If the small box has 10 cups, then:
(small) 10 cups = 100%
(medium) x cups = 130%
Now, cross multiply:
10 (130) = x (100)
1300 = 100x
x = 13
Another way to solve this is by turning 30% into a decimal:
30/100 = 0.3
10 (0.3) = 3
Now you have 30% of the 10 cups, but you need 30% more than the small box, so:
10 + 3 = 13 cups